1. Field of the Invention
This invention relates generally to surgical clips and clamps, and clinches adapted for use with sutures.
2. Discussion of the Prior Art
In the surgical environment, clips and clamps have been used for removably holding two objects in close proximity. These objects may include tissue, vessels or other surgical devices such as sutures. Clips and clamps may be of the variety disclosed and claimed by Applicant in U.S. Provisional Patent Application Ser. No. 60/040,655, filed Mar. 10, 1997, and entitled xe2x80x9cSurgical Clips and Clampsxe2x80x9d. Suture clinches of the past are well represented by Applicant""s U.S. patent application Ser. No. 09/082,495, filed May 21, 1995, and entitled xe2x80x9cSuture Clinchxe2x80x9d. Both of these applications are incorporated herein by reference. In the latter application, a metal clinch is disclosed to be stamped from a sheet of metal and pre-formed to operate with an associated clinch applier. The two free ends of a suture are disposed within the clinch, which is then slid down the suture ends and crimped to bind the suture ends in a fixed relationship. As used herein, the word xe2x80x9cclipxe2x80x9d refers not only to clips, but also to clamps, clinches, and other surgical devices adapted for use in the foregoing methods.
In the case of the metallic clinches of the past, the metal-to-suture interface tends to provide a coefficient of friction that initially is too high to facilitate the sliding step of the process, and ultimately is too low to lock the suture ends in a fixed relationship.
In accordance with the present invention, a coating is provided on the clip in order to facilitate one or more of the steps in its method of operation. With respect to a suture clip, a coating is contemplated which would initially facilitate the sliding step by providing a reduced coefficient of friction with the suture ends. Another type of coating might provide an increased coefficient of friction with the suture ends, thereby facilitating traction enhancement during the locking step. More than one layer of material may be included in the coating, to facilitate both the initial stage as well as the ultimate stage of operation.
Any coating applied to a suture clinch would tend to function as an occlusive cushion to inhibit abrasion between sharp edges and corners of the clinch, and the suture material. For traction enhancement, any material can be used as a coating to produce an increased coefficient of friction with the suture material. In a preferred embodiment, the material chosen is identical to that of the suture material, since similar or identical materials normally exhibit increased frictional resistance to slipping. A more compliant material might be chosen for the traction enhancement coating in order to increase the area of contact between the clinch and the suture. By increasing the area of contact, elevated compressive pressures need not be applied to securely hold the suture.
The traction enhancement coating might also be selected to enhance the holding ability with a resorbable suture. This permits those portions of the suture distant from the clinch to be resorbed, while the suture in the clinch is protected from the resorption process. In preferred embodiments, the traction-enhancing coating includes plastics such as polypropylene or polyethylene.
A lubricious coating could be applied to facilitate the sliding of the clinch along the suture ends. In this case, a reduced coefficient of friction is desirable. A coating of hydrophilic or hydrophilic-hydrophobic material is contemplated to provide the desired lubricity.
In a further embodiment, the clinch is coated with two layers of material in a laminate. The first layer is coated on the metallic clinch to provide traction enhancement. The second layer is coated on the first layer. Initially, the second layer contacts the suture and provides the desired lubricity for sliding the clinch into place. With a hydrophilic coating, moisture is attracted to provide the desired lubricity. As the second layer is ablated by movement of the suture during the sliding step, the first substrate is exposed and ultimately compressed against the suture in the locking step. Alternatively, the second layer may be displaced by the compression of the clinch upon the suture. In either case, once the clinch is operatively disposed in its desired position, the first traction-enhancing coating engages the suture ends to lock the suture.
The coatings can be applied in accordance with any known method for coating objects. Dip-coating is initially contemplated, but dispersions, solid castings, insert moldings, and spraying may also be appropriate. The coatings can be separately formed and adhered to the metallic base in a further process. Typically, the laminate or coating will be applied to the clinch while it is in a flat-formed condition.
These and other features and advantages of the invention will be better understood with reference to certain preferred embodiments and the best mode of the invention, taken in combination with the associated drawings.